In the past (Netburst era), AMD has flat-out beaten Intel in performance, despite a lower R&D budget. Despite notable missteps, they seem to be pretty good at getting the most out of their R&D dollar. No, they won't beat Intel outright this time (their last victory was assisted by Intel's own stupidity in pushing Netburst and Itanic, a mistake they won't make again), but I do expect them to return to a level where they can actually compete in the high-end laptop/AIO, HEDT and server markets, rather than just bottom-feed as they are doing now with the construction cores.
And let's not forget that they are trying to match an IPC target that has only barely budged since 2011. It's easier to catch up to a competitor than to blaze new ground. AMD also had the advantage of being able to pick and choose the best aspects of three different ground-up architectures (K10, cat cores, and construction cores) when designing Zen. They probably knew quite a bit from the start about what should be done and what should be avoided.
On the top quad-core bin, absolutely. If they stick with a maximum 95W TDP as leaks indicate (was this ever put in an official document), then an 8-core CPU won't be going that high at stock. But it should still overclock to that level just fine. Intel's 22nm process is inferior to Samsung/GloFo 14LPP in every metric, but 8-core Haswell-E clocks to 4.0-4.5 GHz just fine if you're willing to tolerate 140-160W power consumption. And that chip has a beefier AVX unit than Zen (at least if Dresdenboy's inferences are accurate), and we know AVX is one of the most power-hungry features of a modern CPU.